This is a flannel shirt from FranCisT MOR.K.S. The size is 4, which is a Japanese L. This is a favorite brand often worn by Mr. Children's Kazutoshi Sakurai. It fit me perfectly, so I'd say it's about a men's M. Black and white checkered flannel shirt, perfect for casual style. - Color: Black and white check - Design: Collared, button closure, with shoulder decorations - Material: Flannel - Style: Casual - Decoration: Floral embroidery on the chest - Sleeves: Cuffed Thank you for looking. #FranCisT MOR.K.S. #MrChildrenSakurai Mr.Children Kazutoshi Sakurai